A long-term reconstruction of temperatures in the Pacific Ocean reveals how its heat content has changed since the last glacial era — findings that could augment climate models.

Yair Rosenthal at Rutgers University in New Brunswick, New Jersey, and his colleagues analysed sediment cores in Indonesia's Makassar Strait, and used the mineral composition of tiny sea creatures' shells to calculate past water temperatures.

This showed that, at depths of 500–900 metres, temperatures in the Pacific Ocean were typically higher over the past several thousand years than at present. Over millennia, the waters have undergone prolonged cooling and temperatures are now increasing faster than at any time in the past 10,000 years.

The results support other studies suggesting that the ocean is currently taking up more heat, temporarily slowing the rise in average global air temperatures.

Science 342, 617–621 (2013)